In known X-ray image diagnosing apparatus having a C-arm type holder unit, an X-ray generating section and an X-ray detecting section are arranged at the respective opposite ends of the C-arm. A transparent image and a photographic image are displayed on a display monitor as a function of the dimensions of the X-ray detector (I.I: image intensifier or FPD: flat panel detector) and the values specified for visual field size.
In recent years, efforts have been paid to raise the level of diagnosis and therapeutic manual procedures by arranging a compact high-resolution X-ray detector in addition to an ordinary X-ray detector that provides an image size of about 8 to 16 inches in order to obtain a clearer image of a region of interest (ROI) such as a morbid area.
Apparatus having two X-ray detectors includes those having a switching arm mechanism disposed in the X-ray detecting section of the apparatus to place, when necessary, the compact high-resolution detector in front of the ordinary visual field size X-ray detector to collect high-resolution images but, when not necessary, retract the high-resolution detector.
The switching arm mechanism of this configuration is arranged so as to make the center of the image obtained by means of the ordinary X-ray detector agree with center of the image obtained by means of the compact high-resolution detector and the images obtained by means of the two detectors agree with the center of the focus of X-rays.
With an X-ray image diagnosing apparatus equipped with a compact high-resolution detector having a small visual field, the visual field becomes small as the ordinary X-ray detector is switched to the compact high-resolution detector. Thus, either the ROI needs to be aligned with the image center before selecting the small visual field or, after selecting the small visual field, the C-arm needs to be driven or the bed needs to be moved for an adjustment operation of putting the ROI into the small visual field. This gives rise to a problem of making the system rather inconvenient and the therapeutic manual procedures inefficient.
On the other hand, there are known X-ray image diagnosing apparatus having two X-ray detectors of the type where the operator of such an X-ray image diagnosing apparatus specifies the spot he or she wants to look at in detail, for example, the position where a stent 4 is buried in a blood vessel 3, on X-ray image 1 obtained by means of the ordinary X-ray detector by means of a marker 2 so as to make the spot includes the ROI.
Then, only the compact high-resolution detector is moved according to the coordinate data of the specified marker (ROI) and the whole image is displayed, including the ROI part that is displayed as a high-resolution image. However, with such an X-ray image diagnosing apparatus, the ROI image can be displayed at a side position in the displayed whole image to make it inconvenient for image diagnosis.
In such an instance, the operator is required to carry out an additional operation of making the ROI part displayed at the center of the whole X-ray image. Furthermore, from the structural point of view, a complex switching arm mechanism is required for such an operation because it needs to have an independent drive mechanism for moving only the compact high-resolution detector.
Therefore, the object of the present invention is to dissolve the above-identified problems and provide an X-ray image diagnosing apparatus that can carry out an examination operation promptly if a compact high-resolution detector having a small visual field is employed in it.